Birkat Hamazon, The Blessing on Nourishment, known in English as the Grace After Meals, is a benching book used for daily prayer. It is a set of Jewish blessings that Halakha prescribes following a meal that includes at least an olive sized piece of bread or matzah made from one or all of wheat, barley, rye, oats, spelt. It is a mitzvah de-'oraita, that is written in the Torah (Deuteronomy 8:10).